Photodynamic therapy of nonmelanoma skin malignancies with topical delta-amino levulinic acid: diagnostic measurements

Photodynamic therapy (PDT) using topical application of the Protoporphyrin IX (PpIX) precursor (delta) -amino levulinic acid (ALA) in various malignant skin tumors is a new promising treatment modality. We have treated an extensive number of non-melanoma malignancies of the skin over the past three years with very satisfying initial results. For superficial, shallow lesions one treatment session is sufficient. In thicker lesions, such as nodular basal cell carcinomas, complete treatment response is achieved after two or three treatment sessions. In conjunction with the treatment procedure the tissue fluorescence and the superficial blood flow have been investigated during and after the treatment procedures. The PpIX build-up has been detected in vivo and the degree of tumor selectivity has been evaluated using laser-induced fluorescence. Also changes in the bloodflow in tumors compared to normal skin before, during, and after the treatment procedure has been followed using a laser- Doppler perfusion imaging system. Results from the measurements in basal cell carcinomas (BCCs), Mb. Bowen lesions (squamous cell carcinoma in situ) and cutaneous T-cell lymphoma lesions are presented.